html,body,#app{
  height: 100%;
  width: 100%;
  margin: 0;
}

.wh100{
  width: 100%;
  height: 100%;
}

.bg{
  background-image: url(https://students-list.oss-cn-hangzhou.aliyuncs.com/hz-bg/hz-bg-176.png);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}

.bg-opacity{
  background-color: rgba(0,0,0,0.0);
}